15min:
A NEW POTENTIAL ENERGY SURFACE FOR H2--N2O AND PIMC SIMULATION PROBING SUPERFLUIDITY AND VIBRATIONAL FREQUENCY SHIFTS IN DOPED para-H2 CLUSTERS.

LECHENG WANG, ROBERT J LE ROY AND PIERRE-NICHOLAS ROY, Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada; DAIQIAN XIE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu, China.

The existence of superfluidity of para-hydrogen clusters doped by the linear molecules,,~ such as CO, CO2 and OCS stimulated our theoretical study of (para-H2)N--N2O clusters. A new 6D ab initio PES for the H2--N2O dimer which explicitly included the symmetric and asymmetric vibrational coordinates Q1 and Q3 of N2O was constructed. Four-dimensional global intermolecular PESs were then obtained by fitting the vibrational averaged interactions energies for nu3(N2O)=0 and 1 to the Morse/Long Range(MLR) analytical form with theoretically fixed long-range parameters. Using the adiabatic hindered-rotor approximation, effective two-dimensional PESs for the para-H2--N2O dimer were then generated. Predictions of the infrared spectra of para-H2--N2O based on these PESs have been in good agreement with the experimental observations.~ Based on these surfaces, predictions of structural properties, vibrational band origin shifts, rotational dynamics and superfluidity of (para-H2)N--N2O clusters have been generated using bosonic PIMC simulation methods. The evolution of the calculated shifts agreed reasonably with that for the experimental observations.~ Reduction of the effective moment of inertia is predicted to occur when the dopant is partially surrounded by the para-H2 solvent, which marked the onset of molecular superfluidity in para-H2. Results obtained using our surfaces and PIMC algorithm will be presented.